In the practice of dentistry it is frequently necessary to fill a void left in a patient's mouth by a missing tooth. This is done by fitting an artificial tooth in an operative position to support the chewing function.
A single artificial tooth may have a cantilever support from a single adjacent tooth, or be supported in a bridge structure from the natural teeth on both sides. A permanent bridge may also replace several teeth.
When a tooth has first been pulled it is necessary for the dentist to provide a temporary replacement for it, so as to protect the patient's gums during the healing process and also provide time for a dental laboratory to fabricate the permanent replacement. Such a temporary replacement for a missing tooth is known in dentistry as a pontic. Practicing dentists at present find it necessary to fabricate each temporary replacement tooth or pontic on a custom basis, usually while the patient is sitting in the dentist's chair. The shape and location of the replacement tooth are established in several successive steps, culminating in the final step of fastening the replacement tooth in position by securing it to one or both of the adjacent teeth. This procedure is quite time consuming for the dentist and is no particular pleasure for the patient. But yet the temporary tooth is simply thrown away when its permanent replacement becomes available.
Furthermore, a common problem is that the temporary tooth falls out, because it was not well fitted or was not well supported, thus necessitating a repetition of the temporary procedure. This entails extra work which the dentist would prefer to avoid.
When possible, it is desirable for the dentist to provide replacement teeth that are gnathologically correct. Each such tooth should have the correct position and aspect, involving a total of six possible adjustments. Furthermore, the chewing surface of the tooth needs to be three-dimensionally correct relative to the patient's jaw movement pattern. These requirements present a challenging demand for the dentist.